Large, multi-satellite communication systems are expensive to build and place into orbit. Because of the expense, it is desirable to fully utilize the space-based resources to provide revenue producing communication services to users and to minimize the amount of resources that are not providing services to users.
A "satellite" is defined herein to mean a man-made object or vehicle intended to orbit Earth and includes both geostationary and non-geostationary satellites. A "constellation" is defined herein to mean an ensemble of satellites arranged in orbits for providing specified coverage of a portion or all portions of the Earth. A constellation typically includes multiple rings (or planes) of satellites and can have equal numbers of satellites in each plane, although this is not essential. A constellation could include geostationary or non-geostationary satellites, or a combination of both.
In many instances, calls are made between subscriber units that belong to the same system. Generally, the subscriber units are compatible only with one type of communication system. For example, Global System Mobile (GSM) subscriber units require a GSM compatible base station, and Code Division Multiple Access (CDMA) subscriber units require a CDMA compatible base station. In order for these non-compatible subscriber units to be connected to each other, a terrestrial-based link must be established between base stations. This is not always possible to accomplish for a variety of reasons, some of which are politically motivated.
In prior art systems, communication resources are put into service based on predicted utilization from a number of system compatible users located around the world. Because these predictions, by their nature, are somewhat inaccurate, some system resources are under-utilized when system resources are allocated according to the predictions.
What are needed are a method and apparatus for allowing terminals to communicate with each other using system resources provided by a satellite communication system. Further, what are needed are a method and apparatus for allowing non-system-compatible terminals to use system resources to increase the revenue generating utilization of a satellite communication system.